Synthesis, Microstructure, and Diffraction Efficiency of Photopolymerizable Silica for Optical Storage

• Main Authors: Szu-Ming Teng, 鄧斯名
• Other Authors: Tzu-Chien Hsu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/61337789895516398663

碩士 === 國立中山大學 === 材料與光電科學學系研究所 === 100 === A series of photopolymerizable silica for optical storage has been prepared using sol-gel process in this study. The inorganic-organic hybrid materials were based on methacroloxy-propyl-trimethoxysilane (MPTS) and tetraethylorthosilicate (TEOS). Thin films of the hybrids were prepared using spin coating, knife coating, and the closed-mold methods, while the knife coating showing better film flatness and controlled film thickness. Results indicate crack-free polymerizable silica can be obtained using a recipe with 1 wt% photoinitiator. Samples after irradiation shows increased transmittance, suggesting that photopolymerization did take place with the aid of photoinitiators. Spectroscopic study from FTIR indicates C=C conversion in the acrylic part of MPTS reaches 57.51%. The grating period is observed by the optical microscopy. The maximum diffraction efficiency is 48.21%, as obtained from the sample of pure MPTS. From BET measurements, the pore size of the polymerizable silica increases with the increasing amount of MPTS, consistent with the results from measurements of apparent density. Factors affecting the diffraction efficiency are analyzed; these include sample flatness, sample thickness, the conversion of monomer, and concentration of the photoinitiator. Formation mechanism of the periodic grating is proposed based on this study. Addition of MPTS can greatly alleviate problem of phase separation; yet, movement acrylic segment in MPTS is severely limited. On the other hand, samples with more TEOS tend to be densified more with decreased diffraction efficiency